1. Field of the Invention
The present invention relates to a coil segment manufacturing apparatus and a coil segment manufacturing method for manufacturing coil segments, which have a plurality of different lengths, and the insulation coatings of both ends of which have been removed, from a coil conducting wire material provided with an insulation coating.
2. Description of the Related Art
Conventionally, such coil segments are used to form a stator coil. To form the stator coil, a number of coil segments formed substantially into a U shape are arranged in an annular shape, the central portions of the U-shaped coil segments being overlapped, and both ends of the U-shaped coil segments are inserted into the slots of a stator core. Thus, the ends of each coil segment project from each slot. Then, the projecting ends of the coil segments are joined to constitute the stator coil (refer to, for example, Japanese Patent No. 3894004).
Further, a plurality of coil segments used in the form of a bundle have also been known (refer to Japanese Patent Application Laid-Open No. 2012-165624). Each bundle of the coil segments is formed into a U shape. A plurality of the formed coil segment bundles are annularly arranged such that they partly overlap, and both ends thereof are inserted into the slots of a stator core. The end portions of the coil segments that project from the slots are bent and joined to corresponding ends, thus constituting a stator coil.
To constitute the stator coil by using the foregoing coil segment bundles, the corresponding ends of the coil segments are joined. Therefore, when the coil segments constituting each bundle are inserted into the slots of the stator core, the portions that project from the slots are required to have the same length.
A possible method for obtaining the same length is to cut the ends of the bundled coil segments to the same length after the coil segments are formed into the bundle. However, the bundles of coil segments that have been formed are not linear, thus requiring a complicated apparatus for cutting the ends of the bundles to the same length. As a possible alternative method to obviate the need for using such a complicated apparatus, coil segments for constituting a bundle are set to different lengths beforehand such that the end portion of a bundle will be the same after the bundle is formed.
However, manufacturing a large volume of coil segments having different lengths would require that a cutting apparatus be used for each different length, meaning that separate apparatuses be used for different lengths, as well as an apparatus for gathering coil segments one by one of different lengths into a bundle. In addition, the processing by such an apparatus requires a certain time, leading to deteriorated manufacturing efficiency.
Further, both end portions of the coil segments must be in a state such that the insulation coatings are removed. This may be implemented by first removing the insulation coating of a portion of the conducting wire material that will be cut and then cutting the conducting wire material at the portion in the process of feeding and cutting the conducting wire material.
In this case, if the lengths of the coil segments are the same, then a feeding operation, in which the conducting wire material is fed by a predetermined feeding amount, is repeated, and the insulation coating is removed and the conducting wire material is cut at the same timing in synchronization with the repetition of the feeding operation. If, however, the lengths of the coil segments are different, then the removal of the insulation coating and the cutting of the conducting wire material have to be carried out at different timings while changing the feeding amount of the conducting wire material for each feeding operation. This leads to deteriorated production efficiency.